Phenethyl Isothiocyanate (PEITC) is a naturally occurring compound found in cruciferous vegetables. It has been shown in the laboratory and in rats to inhibit 4-(methynitrosoamino)-1-(3-pyridyl)-1-butanone or NNK, a potent carcinogen in cigarette smoke. This Phase I study will determine the maximum tolerated single dose of PEITC; measure the PK of PEITC to predict the daily dosing interval required to maintain a steady state of PEITC in the hours of NNK exposure; and obtain preliminary data on the perturbation of NKK metabolism by PEITC in human beings. The Core Laboratory was utilized for PCR, ELISA and recombinant DNA techniques.